Although every mine has site-specific conditions, the object is usually the same: move the most material as quickly as possible at the lowest cost. In this respect, conveyor system suppliers are giving customers what they want, and more. New drive designs and soft start technology allow mines to keep large overland systems operating reliably under heavy loads while improved transfer point, dust control and individual component design contribute to efficiency and reduce environmental problems. Diagnostic systems will allow operators to pinpoint problems and position conveyors accurately. This will help the mines better plan maintenance and significantly lower the chances for catastrophic failure.

However, technological advances bring issues of their own. With broader choices in drive systems, rolling components and belting, conveyor-system design has reached a new level of sophistication, demanding more involvement and technical savvy from both suppliers and end users.

Chuck Felix, vice president-mining sales for conveyor belt supplier Fenner Dunlop, said, “People can no longer call up and just ask for a 3-ply belt or whatever they think will work. Likewise, the level of expertise that’s required for field sales people has really ratcheted up. About 15 years ago, we started training [our] sales team in belt engineering principles. They were trained to understand why pulley diameters can be a problem and why transition distances need to be correct. They learned how to do a system survey and look for areas of concern. This training has paid off. They are more of an engineering support group today versus a purely sales oriented team.”

Computer-assisted component design and system modeling are becoming industry norms for all but the simplest applications and parts. Continental Conveyor, for example, uses modeling software called Statix to analyze existing conveyor systems and design new ones. “We have the ability to take any length conveyor, knowing the tonnage capacity required, and evaluate tension and horsepower requirements, as well as model its performance using any soft start method selected. This is the critical first step to any successful conveyor installation,” said Rex Waller, director field sales and service, Continental Conveyor.

Sandvik Materials Handling is currently designing and building a 4.5-km-long conveyor system for the new Lumwana openpit mine project in northwest Zambia. SMH is a subcontractor to Ausenco and Bateman Engineering, which holds the engineering, procurement and construction contract for this project.

As part of the design process, discrete element modeling (DEM) is being used to ensure that the system can handle the production tonnages that mine owner Equinox Minerals requires. A computer-aided design audit using an advanced dynamic simulation model also was conducted to validate the design for all conveyors in the system. In total, there will be six conveyors of varying sizes, the largest being an overland conveyor, powered by four 600-kW drives, that will transport crushed ore ranging from fines to 400 mm in size on a 1,350-mm-wide ST2000 steel-cord belt running at 5 m/sec.

Suppliers are also ratcheting up their focus on production efficiency and quality control. As an example, Jim Pecorelli, who heads the North American region for Veyance Technologies—the new corporate entity of Goodyear Tire & Rubber’s former Engineered Products Division—cites the acquisition of the ISF fabric weaving facility in Hogansville, Georgia, USA. Soon after the change of ownership, Veyance decided to bring more weaving capability back in-house so that the company could control a greater portion of the supply chain. The ISF facility has been renamed Specialty Fabric & Converting.

“The ISF acquisition will give us the capability to do all of our weaving for North America,” Pecorelli said. “We have an opportunity to install technology into the facility. It is already providing greater reliability for the supply of fabric to the belting facilities in Marysville, Ohio, and Bowmanville, Ontario. It’s providing us with a greater quality product with more control over width and length. It also ensures that we keep our proprietary weaving and dip technologies in-house.”

Veyance Technologies has other projects under way that are expected to quickly yield additional benefits. The company has invested between $15-$20 million at its Marysville facility, which supplies most of the conveyor belting for mining, to modernize processes and equipment. “We started off quietly in late 2006 with a twophase approach to modernizing that facility,” Pecorelli said. “The first phase is already completed and we are seeing the benefits. The second phase will be completed in the third quarter of 2008.”

The company believes that these improvements will provide it with an industry- leading approach to conveyor belt manufacturing. “We will transition from a batch-oriented process to inline processing that will significantly increase the amount of automation and provide a much more reliable first-run yield off of the equipment,” Pecorelli said. “What that means to our distribution and end-users is gauge control—better width and length control— and more reliable delivery.”

Veyance currently manufactures conveyor belts in six countries: the U.S., Canada, Australia, South Africa, Brazil and Chile. “We have a well-established presence within China,” Pecorelli said. “We have moved our corporate office for the Asian Pacific region from Australia to Shanghai. We have a procurement team and a supplier development team. That team is working to gain us a much better presence in China.”

Although the Engineered Products division is no longer part of parent company Goodyear Tire & Rubber, Veyance will continue to use the Goodyear Engineered Products brand name, under license, for the foreseeable future.

Fenner Dunlop plays an active role in the design of conveyor systems by partnering with the conveyor system OEMs. “We recommend the correct belt to optimize the efficiencies of a system,” Felix said. “As an example, a critical element is the pulley diameters which can have a negative impact on the longevity of a conveyor belt. By working together we can eliminate potential trouble spots for the end user. This brings an engineering solution to what has been an issue in the past.” Anymore with these high-tension systems, designing a conveyor gets fairly technical.

Fenner Dunlop, like Goodyear’s conveyor division, has undergone organizational changes but believes it ultimately has emerged as a stronger company. “The company came through quite a few acquisitions,” Felix said. “Fenner purchased Nationwide Belting in 1996, and then Scandura a year later. Then they bought Unipoly [Georgia Duck] in 2000. As we have seen with many companies, these consolidations and acquisitions can be a tense time with divergent cultures,” he explained, but the company has been able to “ramp up to meet the challenge” of incorporating the acquisitions as well as the demand from booming coal and hardrock mining markets.

One example of this effort, said Felix, is “a $90 million investment in two of our plants in the U.S. We’re putting a large addition into the Port Clinton facility in Ohio, which will cost approximately $50 million. We’re building a weaving facility in Georgia that is on the order of $40 million. We are going to have the most efficient weaving facility for conveyor belt fabric in the world. We will have two brand new, state-of-the-art, 96-inch belt press lines in Port Clinton.”

Drives and Couplings: A Solution for Every Job
Although most mine-site conveyor installations have unique site characteristics or performance requirements, there are a number of common factors that must be known or assumed by the conveyor designer before starting work on the system and specifying the type of drive(s) needed. Some of these factors include product through-put, belt speed, conveyor length, product size, lift height if applicable, type and size of belt and type of belt support. Other considerations range from whether production will be continuous or intermittent, belt speed constant or variable and conveyor duty cycle to environmental and safety issues. Although most heavy-duty mine conveyors are electrically powered, hydraulic drives have become a viable solution for some specific applications.

Goodyear’s Easyrider was recently installed on the single largest conveyor belt flight in the world
at Curragh North in Australia (20-km long, 40 km total).

The conveyor will be driven by a Gemini system from Hägglunds Drives, consisting of three Compact CBP 840 and Gemini drives with five pump units, giving a combined output of 2,500 kW. The pumps, electric motors, tanks and filter units will be housed separately in a hydraulic room. Having fewer but larger filters and oil coolers, combined with tandem pumps, ensures a clean, easy-to-service solution without unnecessary piping, according to the Swedish supplier.

“Hägglunds has improved the accessibility of each module, as well as increasing the efficiency of each motor. We’re constantly looking for ways to use energy more efficiently, so the high efficiency of the new generation of hydraulic motors was a clear advantage—especially as we can rely on them to work in all situations,” said Jan Lundgren, project manager for LKAB. Commenting on Hägglunds’ ongoing role in drive maintenance, Lundgren said: “They understand the needs and wishes of our technicians and can look after themselves when they are here.”

Bonfiglioli, another supplier of power transmission equipment for heavy industrial applications, said its new HDO Bevel Helical drive units are the result of more than three years of development. According to Bonfiglioli Transmission (Australia) Managing Director Malcolm Lewis, the new models are designed to provide outstanding reliability and torque densities.

“The new drives feature excellent torque distribution across their entire ratio range, with gear ratios laid out in close progression and the drives having a rugged capacity to cope with the shock and impact of intermittent loads,” Lewis explained.

Lewis said Bonfiglioli applied both Finite Element Analysis and MultiBody Simulations to the design of the HDP Parallel Shaft and HDO Bevel Helical units, both available in sizes up to 72,000 Nm. These studies were used to identify the stress pattern on each of the main components and to optimize the design for s structural stiffness, gear geometry, shaft deflection, and to extend gear and bearing lifetime.

Units up to size 120 (35,000 Nm) feature rigid monoblock housings while larger units feature a horizontally split housing. According to the company, the A series bevel helical gearboxes are part of a range with drives so compact that one unit can be used in applications traditionally requiring two gear units combined. The A series—offered in 12 sizes from 0.9-55 Kw and 150 Nm-14,000 Nm torque—features a ratio range up to 1700:1 in a single gearbox, with four reduction stages.

Voith recently debuted its TPKL-T turbo coupling for users who want an alignmentfree drive solution. The actual drive, made up of the motor, coupling and gearbox, is centrally supported using a standard torque-arm support below the drive. This means that not only the Voith turbo coupling, but the entire drive can easily be attached to and detached from the drive pulley on site.

Since they were introduced in 1998, TPKL couplings have proven to be reliable, according to Voith. It was specially developed as a compact drive solution for belt conveyors. It has been installed in more than 250 drives with a power range up to 250 kW (1,500 rpm) or up to 430 kW (1,800 rpm). Since it was first launched, the series has been supplemented to enable Voith turbo couplings featuring fill control technology to be used on belt conveyors with an individual drive power of 2,400 kW (1,200 rpm) or 4,700 kW (1,500 rpm).

The new TPKL-T fill-controlled turbo couplings are fed by an external oil supply system. The oil supply system is located near the drive assembly and uses several flexible hydraulic hoses for easy assembly and connection to the TPKL-T housing and oil cooler, which allows the oil supply system and associated electrical components to be placed conveniently in the general area of the coupler. Relocating those items also gives maintenance personnel better accessibility around the drive.

New Belts are Energy Misers
Mines are always searching for ways to cut their costs, and a conveyor system’s rolling resistance has a huge impact on energy costs, especially for long overland conveyors. To address this problem, Goodyear Engineered Products developed its Easyrider rubber belt cover in 2006 and the company has sold 400 km of it since. Easyrider’s compounding technology is designed to absorb energy at every roller. Each roller represents a minute frictional loss, but it adds up over a conveyor’s length.

“We have documented and proven with careful monitoring that Easyrider saves between 6% and 20% of the energy required to move the belt,” said Mike Braucher, belt marketing manager, Veyance Technologies. “That’s a significant savings in operating costs. It’s not just a one time savings, it’s an annual savings. As long as the mines run the belt, they are going to have an energy savings over what they would have used prior to this innovation.”

The company is planning new product introductions for MINExpo 2008. “We will use RFID chip technology to inform the end-user as to when and how to perform maintenance. They will be able to position belts very accurately.” Spotting a rip on a 20-km conveyor could be difficult. “With these systems, it’s ease of use,” said Braucher. “An operator can sit at a computer and monitor various criteria on the belt, such as the amount of cover remaining. It’s more preventive and proactive than what we had in the past.

“In the past, a sensor system would tell the operator the belt is ripped and shut it down,” said Braucher. “We will offer a system that monitors the belt so that mine operators can identify problems before they happen. Quick analysis will tell the operators that they might need to replace a portion of the belt or that they might have some problems in the future and to budget time to do some maintenance work.”

In addition to its MineFlex, MineHaul and Goldline PVC mining belt products, Fenner Dunlop also offers the rEscan remote conveyor monitoring system, a permanently installed conveyor interrogation tool designed to look for internal cord damage and internal splice lay-up on steel cord conveyor systems. Early detection, mapping and monitoring of damaged areas and splices allow mine maintenance engineers to plan maintenance windows in advance, and extend the service life of the conveyor systems under their control.

rEscan works via phone line or LAN connection, without stopping production. The front-end of the system comprises of a set of two “conditioning” transducers (permanent magnets), a “sense” transducer and a tachometer. As the belting passes the conditioning transducers a magnetic field is induced into the steel ropes within the belting. Any breaks or corrosion produce small magnetic fields that induce voltages within the sense transducer. These voltages are then passed back to the Main Computer Housing. The tachometer is mounted to a nearby roller to measure the distance of the belt passing by.